1. Field of the Invention
Nucleate boiling enhancement, especially in flooded liquid chillers using a halocarbon refrigerant.
2. Description of the Prior Art
Various techniques have been employed to enhance the formation of nucleate boiling in flooded evaporators such as those comprising a tube bundle immersed in a halocarbon refrigerant such as R-12 or R-11. Examples of such techniques include scoring or artificially roughing the tube surface, providing a sintered, porous surface coating as described in U.S. Pat. No. 3,384,154; using bent over fins to provide re-entrant cavities such as described in U.S. Pat. No. 3,454,081; and the use of inserts between the spaced fin surfaces as described in U.S. Pat. No. 3,521,708, issued to R. L. Webb on July 28, 1970. In Webb, radially extending fins are first formed in a conventional manner, such as by commercial finning equipment; and then the space between adjacent fins is wrapped with a solid, homogenous insert to produce a narrow gap between the insert and the fin surface.